1. Field of the Invention
This invention relates to additives for lubricants and normally liquid fuels. More particularly it relates to additive compositions which are formed by esterifying an alcohol with a high molecular weight carboxylic acid reagent derived from an oxidized, degraded ethylene-propylene interpolymer and a low molecular weight ethylenically unsaturated carboxylic acid reagent. The invention also pertains to lubricant compositions, normally liquid fuel compositions and additive concentrate compositions containing these additive esters.
2. General Background
The improvement of performance properties of lubricants and normally liquid fuels by the addition thereto of certain materials known as additives is well known in the art. See for example, Smallheer and Smith "Lubricant Additives" published by Lezius-Hiles Corporation, Cleveland, Ohio, and Gruse "Motor Oils" published by the Reinhold Publishing Corporation of New York, particularly pages 160-203. Specifically, it is well known that a lubricating oil's viscosity-temperature interrelationship can be improved by addition to the oil of a viscosity improving agent. Similarly, it is well known that the ability of an oil or a liquid fuel to disperse the sludge formed in it can be improved by addition to the oil or fuel of certain relatively high molecular weight organo-nitrogen additives. Still further, it is known that the VI and dispersant functions of such additives can be combined in a single molecule composition. One class of such materials which are nitrogen-containing polyacrylates and polymethacrylates are sold by the Rohm and Haas Company of Philadelphia, Pennsylvania, under the trade name "Acryloids".
Increasing attention to the problems of air pollution and more specifically those problems arising from combustion of organo-nitrogen compounds has led to a search for effective viscosity improving and sludge dispersing agents in which only carbon, hydrogen and oxygen are present in substantial amounts. One such class of sludge dispersing agents comprising certain succinate esters is disclosed in U.S. Pat. Nos. 3,331,776, 3,346,354 and 3,381,022. Graft copolymers made by reacting unsaturated carboxylic acid esters of alkane diols are also known to be effective carbon-, hydrogen- and oxygen-containing dispersants and VI improvers. See, for example, U.S. Pat. No. 3,687,849. The present invention is directed to a third type of multifunctional viscosity improving, sludge dispersing and cold flow improving additives.
3. Prior Art Patents
In addition to the hereinabove-noted patents, the following U.S. Patents provide background for the present invention. U.S. Pat. No. 3,388,067 discloses lubricant compostions containing hydroxylated, degraded ethylene-alphaolefin interpolymers. U.S. Pat. Nos. 3,389,087 and 3,551,336 describe oil compositions containing ethylene-alpha-olefin copolymers with varying distinguishing characteristics such as crystallinity and specific chain conformations. U.S. Pat. No. 3,769,216 discloses lubricant compositions containing additives derived from degraded ehylene propylene copolymers-alkylene polyamines reactions. Finally, U.S. Pat. No. 3,316,177 discloses lubricating oils containing polyamine salts of the reaction product of maleic anhydride and oxidized, degraded ethylene-propylene interpolymers.